This invention relates to a method for filling gas into a sealed cylinder device having a telescopically movable rod, such as a gas spring or a hydropneumatic shock absorber or the like.
In one prior art gas spring arrangement, one end of a cylinder is closed by a cover plate sealingly secured thereto by welding. A piston is fitted slidably in the cylinder, and a rod secured to the piston extends outside of the cylinder sealingly through a rod guide secured to the other end of the cylinder. The interior of the cylinder is filled with oil and compressed gas (usually, nitrogen). For filling the compressed gas into cylinder, an opening is formed in the cover plate and the gas spring is located in an atmosphere of gas under a predetermined pressure thereby allowing gas to flow into the cylinder. Thereafter a plug is sealingly fitted in the opening and secured to the cover plate such as by welding in the atmosphere.
In in case, difficulties are encountered such that the system for enclosing at least a portion of the gas spring within the atmosphere and performing the welding operation is expensive, and inspection for finding gas leakage during the welding operation is difficult since the welding is performed in the gas atmosphere.